Copper (Cu) is a naturally occurring metallic element found in soil, rocks, and water. The human body requires this trace mineral for numerous physiological functions. However, consuming copper in excess, particularly from drinking water, can lead to health concerns. Understanding when copper moves from beneficial to harmful is necessary for public health protection.
Copper’s Role as an Essential Nutrient
Copper acts as a cofactor for several enzymes, known as cuproenzymes. These enzymes are necessary for cellular energy production and for synthesizing connective tissues, such as collagen and elastin. Copper also plays an important role in iron metabolism, helping the body absorb iron and build red blood cells.
Additionally, it is a component of superoxide dismutase, an enzyme that neutralizes free radicals. Maintaining a stable level of copper is important because both deficiency and excess can disrupt metabolic processes. The Recommended Dietary Allowance (RDA) for adults is 900 micrograms per day, typically met through a balanced diet.
Primary Ways Copper Enters Drinking Water
High copper levels in drinking water rarely result from source water contamination. Instead, they primarily result from the corrosion of household plumbing. Copper pipes, a standard material for decades, and brass fixtures containing copper alloys are the main culprits.
Corrosion occurs when water chemistry is aggressive, characterized by low pH (acidity), low mineral content (soft water), or high water temperature. When water sits stagnant in these pipes, such as overnight, copper leaches directly into the water supply. Newly installed copper plumbing is often more susceptible to leaching before a natural protective mineral coating forms on the interior.
Health Risks Associated with High Copper Levels
Exposure to high copper levels in drinking water can lead to both immediate and long-term health issues. Acute exposure, often from a single high dose, primarily affects the gastrointestinal system. Symptoms include nausea, vomiting, stomach cramps, and diarrhea, which typically resolve once copper intake stops.
A common visual indicator of high copper levels is the appearance of blue-green stains in sinks and on plumbing fixtures. Chronic exposure (long-term ingestion of elevated copper) can result in more severe systemic damage. The liver is the main target organ for chronic toxicity, potentially leading to hepatotoxicity, liver failure, and kidney dysfunction.
Vulnerable Populations
Certain groups are more susceptible to the toxic effects of copper than the general population. Infants under one year old are at higher risk because their bodies absorb a greater proportion of ingested copper and have less developed excretion mechanisms. Individuals with genetic conditions, such as Wilson’s disease, are also vulnerable. This condition impairs the body’s ability to properly excrete excess copper, leading to its accumulation in the liver and brain.
Setting Safe Limits and Practical Mitigation Steps
Regulatory bodies have established guidelines to protect against copper exposure in drinking water. The U.S. Environmental Protection Agency (EPA), under the Lead and Copper Rule (LCR), has set the copper Action Level at 1.3 milligrams per liter (mg/L). This level is a trigger that mandates public water systems to implement corrosion control treatments if more than 10% of tested taps exceed it.
Homeowners concerned about copper levels should arrange for professional water testing to accurately determine the concentration. A simple action is to flush the cold water tap for 30 seconds to two minutes before drinking or cooking. This clears the water that has been sitting in the pipes and accumulating metals.
Since hot water accelerates corrosion and dissolves more copper, only cold water should be used for consumption, cooking, and preparing baby formula. For persistent high copper issues, point-of-use filtration systems, such as reverse osmosis, can be installed to reduce concentrations.